Disc-form recording media (hereafter, referred to as discs) of a plurality of standards such as a CD (Compact Disc) and a DVD (Digital Versatile Disc) have become widespread. Because these discs have different recording densities, and so wavelengths of light beams used for recording and/or reproduction are different. There are the discs of the same recording density but having different recording and reproduction formats such as reproduction-only, recordable, rewritable, and the like, wherein different recording and reproduction methods are adopted. For this reason, various optical disc apparatuses are used such that the differences in recording densities and recording and reproduction methods are accommodated.
In the case where the optical disc apparatus supports the discs of only one recording density, and one recording and reproduction method, a user must prepare the optical disc apparatus for each disc type. To resolve such inconvenience, there is a demand for the optical disc apparatus supporting a plurality of disc types.
From a viewpoint of miniaturizing the optical disc apparatus, it is ideal that the optical disc apparatus supporting a plurality of disc types comprises one optical head ready for various recording densities and recording and reproduction methods. However, because the wavelengths of the light beams used for recording and/or reproduction are different depending on the recording density, such an optical disc apparatus needs to comprise a plurality of light emitting elements for emitting the light beams. And the discs have different optical systems depending on the standards and the recording and reproduction methods thereof. For this reason, it is difficult to place a plurality of light emitting elements and a plurality of optical systems in one optical head in order to satisfy characteristics necessary for the respective elements and optical systems. In particular, when securing sufficient space required to keep reliability of the characteristics necessary for the respective elements and optical systems, it is difficult to constitute them in one optical head.
For this reason, dividing the optical heads for each wavelength of the light beam or the optical system and recording and/or reproducing the data on a corresponding disc by using each of the plurality of heads enable to make dimensions of each optical head smaller and secure the reliability thereof. Manufacturing and adjustment costs and component costs can also be reduced.
On the other hand, there are many cases where the discs have almost the same outer shape in general although they have different recording densities and recording and reproduction methods, as described above. Therefore, as for the optical disc apparatus supporting a plurality of disc types, it is desirable, from the viewpoint of arrangement space and apparatus costs, to render the elements and structure other than the optical head as common as possible.
Considering these points, it is preferable that the optical disc apparatus capable of recording and/or reproduction on a variety of optical discs have the plurality of optical heads supporting the discs and the commonly used structure other than the optical head.
As for such an optical disc apparatus, Japanese Patent No. 2943918 discloses the optical disc apparatus comprising a plurality of optical heads and one optical disc rotation mechanism. This optical disc apparatus will be described hereafter. As shown in FIG. 37, this optical disc apparatus comprises a first optical head 501a and a second optical head 502b supporting the optical disc capable of recording and/or reproduction, first small guide shafts 502aL, 502aR and second small guide shafts 502bL, 502bR for supporting the first optical head 501a and second optical head 501b on storage respectively, and an optical head storing portion 551 having a turntable 503 and a support 504.
The turntable 503 is rotatably supported about a rotative spindle 503A relative to the support 504, and is rotated in the direction of an arrow 801 by a rotative mechanism not shown. The first small guide shafts 502aL, 502aR and second small guide shafts 502bL, 502bR are placed to be mutually parallel. And the distance from a plane surface including the first small guide shafts 502aL, 502aR to the rotative spindle 503A is set to be equal to the distance from the plane surface including the second small guide shafts 502bL, 502bR to the rotative spindle 503A.
An optical disc 505 is driven by a disc motor 506. When recording and/or reproducing on the optical disc 505, the first optical head 501a or second optical head 501b is radially guided on the optical disc 505 by guide shafts 507L and 507R. The disc motor 506, guide shafts 507L and 507R are integrally supported by a transport base 508. And both the support 504 and transport base 508 are supported by a base 509. The first optical head 501a or second optical head 501b is transported along the guide shafts 507L and 507R by a transport drive (not shown) so as to record and/or reproduce the data by radially scanning the optical disc 505.
The first optical head 501a or second optical head 501b are stored in the optical head storing portion 551 in a state of being supported by the small guide shafts 502aL, 502aR and 502bL, 502bR respectively so that their respective objective lenses 501aA and 501bA are mutually opposed. In FIG. 37, the small guide shaft 502aL and the guide shaft 507L, and the small guide shaft 502aR and the guide shaft 507R are placed in alignment. In this state, the first optical head 501a can be moved from the optical head storing portion 551 to the transport base 508 in the direction of an arrow 802. If the first optical head 501a is inserted into the guide shafts 507L and 507R of the transport base 508, the first optical head 501a records and/or reproduces the data on the optical disc 505 while moving along the guide shafts 507L and 507R.
If the turntable 503 is rotated 180 degrees in any of the directions of the arrow 801 by the rotative mechanism (not shown), the small guide shafts 502bR and the guide shaft 507L, and the small guide shafts 502bL and the guide shaft 507R are placed in alignment. In this state, the second optical head 501b can be moved from the optical head storing portion 551 to the transport base 508 in the direction of an arrow 802. If the second optical head 501b is inserted into the guide shafts 507L and 507R of the transport base 508, the second optical head 501b records and/or reproduces the data on the optical disc 505 while moving along the guide shafts 507L and 507R.
When replacing the optical head, the above-mentioned procedure is inversely performed. In particular, one of the first optical head 501a and second optical head 501b on the transport base 508 is returned to the optical head storing portion 551, and the turntable 503 is rotated 180 degrees. Thereafter, the other optical head is moved to the transport base 508. The optical head is replaced in the case where the optical head on the transport base 508 is not corresponding to the type of the optical disc 505 placed on the disc motor 506. For instance, it includes the case where, as a result of detecting the type of the optical disc 505 placed on the disc motor 506 with the optical head on the transport base 508, it turns out that the optical head is not capable of the recording and/or reproduction.
As described above, this optical disc apparatus requires the turntable 503 to be rotated 180 degrees in the case of replacing the optical head or mounting the optical head not adjacent to the guide shafts 507L and 507R of the transport base 508. For this reason, where W is a larger value of a width Wa or Wb of the first optical head 501a or the second optical head 501b on the surface orthogonal to the rotative spindle 503A of the turntable 503, a height H of the optical head storing portion 551 needs to be at least larger than W. This represents a problem that the height of the optical disc apparatus is restricted by the width of the first optical head 501a or the second optical head 501b and the height of the optical disc apparatus cannot be smaller than W.
A flexible cable 510a such as an FPC (flexible print cable) or an FFC (flexible flat cable) is used for a feeder line and a signal line to the first optical head 501a and the second optical head 501b. For instance, as shown in FIG. 38, the flexible cable 510a is connected to the first optical head 501a, and the flexible cable 510a is curved to the back side of the objective lens 501A. Or else, as shown in FIG. 39, the flexible cable 510a is curved to the objective lens 501A side. And one end of the flexible cable 510a not connected to the first optical head 501a is connected to a printed board not shown by a connector or the like.
In this case, even if the first optical head 501a moves in the direction of an arrow 803 or 804 shown in FIGS. 38 and 39, the flexible cable 510a can be reasonably curved. For this reason, when the first optical head 501a and the second optical head 501b are transported on the guide shafts 507L and 507R, the flexible cable 510a is reasonably curved.
When rotating the first optical head 501a in the direction of an arrow 805 or 806, a force that prevents the flexible cable 510a from being curved is exerted. For this reason, there arises a problem that, in the case where the optical head storing portion 551 is rotated in the direction of the arrow 801 shown in FIG. 37 in the state of having the first optical head 501a and the second optical head 501b stored therein, the flexible cable 510a cannot be adequately curved so that the flexible cable 510a gets damaged or a great force is exerted on a connection between the flexible cable 510a and the first optical head 501a or the connection between the flexible cable 510a and the printed board not shown to destroy the connection.